1. Field of the Invention
This invention relates generally to a connector for connecting coaxial cables which are useable for an antenna feeder and is directed more particularly to a coaxial connector capable of avoiding the hazard of an electric shock by isolating an antenna from a television set with respect to low frequency components.
2. Description of the Prior Art
In a transformer-less television receiver, the antenna should be isolated from the receiver with respect to low frequency components in order to avoid the hazard of an electric shock. To this end, generally a condenser is connected in series with a feeder which connects the receiver to the antenna. To minimize interference caused by undesirable signals which might be picked up by the feeder directly, and to improve the quality of a reproduced picture, it is desired to employ a coaxial cable as the feeder. Accordingly, the antenna is connected to the television tuner through the coaxial cable and isolation condenser combination.
In the prior art, as shown in FIG. 1 of the accomapnying drawings, a receptacle 1a for receiving a section of coaxial cable is formed of a central conductor 2a, an outer cylindrical conductor 3a which is provided with a flange 4a, and insulating material interposed between the central and outer cylindrical conductors 2a and 3a. Another receptacle 1b for receiving another section of coaxial cable is similar in construction to the receptacle 1a and is formed of a central conductor 2b, an outer cylindrical conductor 3b provided with a flange 4b and insulating material between the conductors 2b and 3b. These receptacles 1a and 1b are connected to male connectors which are provided at the ends of the coaxial cables connected to the antenna and tuner (not shown) respectively, to thereby furnish a signal path to the tuner from the antenna. The central conductors 2a and 2b are connected to each other through a condenser 5, and the outer cylindrical conductors 3a and 3b are connected to each other through a condenser 6.
Since the coaxial cable exhibits a very low tendency to pick up undesirable radio frequency signals (for example, a television signal will not be picked up by the coaxial cable other than the television signal which is applied from the antenna), the so-called noise immunity is improved by its use. However, when the condenser 6 is inserted mid-way into the coaxial cable, as described above, undesirable radio frequency signals, which flow normally only along the outer surface of the outer cylindrical conductor 3a, 3b of the coaxial cable, cause a voltage across the lead wires for the condenser 6. This is because of the inherent inductance of the lead wires which permits such voltage to be induced, with the result that undesirable signals caused thereby enter into the inner surface of the conductor 3a, 3b and then flow along such inner surface to be supplied to the tuner. In this case, if the undesired signals are inductively picked up television signals, and if there is a phase difference between these undesirable signals and the normal signals which are supplied to the coaxial cable from the antenna, a ghost image may appear in a reproduced television picture to deteriorate the quality of the picture (this may be caused by the fact that, since the coaxial cable usually is long, there is a time delay for the normal television signal to reach the condenser 6 from the antenna through the coaxial cable whereas there virtually is no delay for the undesirable television signal to be picked up directly by the condenser lead wires.